Some time ago I wanted to create a column that sorts books by date
and time added (or modified) - and I managed to do it (... with a lot of help from others!!). I use it to keep track of changes, new additions, etc.
I know that this is
not exactly what you are looking for, but having a look at that thread might be of some help:
https://www.mobileread.com/forums/sho...d.php?t=238284